Glossary
Ultrasonic water meter
A meter with no moving parts that measures flow with sound. Transducers send ultrasonic pulses with and against the flow, and the difference in travel time gives the flow velocity, from which the meter calculates volume.
Why it matters
It has no impeller to wear or jam, which matters in water carrying sand. It depends on a battery, so battery life belongs in any comparison.
Where it is used
Source
General usage